Particle board is made by depositing a continuous band of fibers and binder on a continuously moving belt, subdividing this continuous band into individual mats, and then pressing the individual mats into rigid panels. The band formation is described in commonly owned patent application Ser. No. 356,298 filed Mar. 10, 1982 now abandoned by Werner Ufermann et al and in the other applications and references cited therein. The press is similarly described in copending application No. 411,109 filed Aug. 24, 1982 by Klaus Gerhardt, now U.S. Pat. No. 4,468,188, as well as in copending applications Ser. No. 719,757, now U.S. Pat. No. 4,645,632 and Ser. No. 719,759, now U.S. Pat. No. 4,647,417, both filed by Friedrich Boettger et al. The deposition and longitudinal subdivision of the mat take place on a moving support surface, but it is normally necessary to arrest the mat to press it.
Thus a transfer conveyor is provided between the continuously moving conveyor belt of the mat-forming equipment and the intermittently moving belt of the press to separate and speed up the mats once they are cut from the band. In a standard system described in German patent document No. 1,166,093 filed Dec. 31, 1960 by Eugen Siempelkamp a single belt conveyor is provided having an upper stretch that terminates at its downstream end at the upstream end of the press conveyor and at its upstream end at the downstream end of the upstream mat-forming conveyor. Means is provided to jointly reciprocate the meeting place or joint at the downstream end of the upstream conveyor and the upstream end of the transfer conveyor, appropriate tensioners being provided to keep the two belts tight. The transfer conveyor is driven part of the time at the same slow speed as the downstream conveyor, and the rest of the time at a substantially higher speed, and the joint is moved at least in the downstream direction generally at the same speed as the downstream conveyor.
The reciprocation of the transfer joint is synchronized with the cutting of the band into mats and with the change in speed of the transfer conveyor so that as soon as a mat moves wholly onto the transfer conveyor, in the fully upstream position of the joint, this joint is moved downstream at the displacement rate of the mat and the transfer conveyor is speeded up. Thus the downstream mat will move rapidly away from the immediately following mat which remains just behind the moving joint. This creates a gap between succeeding mats on the transfer conveyor so that the spaced mats can be deposited on different levels of the press, or so that there is enough time between succeeding mats to stop them and press them. When the joint has moved into its furthest downstream position, the transfer conveyor is slowed down to move synchronously with the upstream conveyor, so the mat at its downstream edge can be transferred by rapid upstream movement of the joint to the transfer conveyor.
Such an arrangement functions well but must be quite long in order to create a sufficiently long gap between adjacent mats. The transfer conveyor can only operate at high speed when a mat is not bridging the joint, so that during this time it must operate slowly. In addition this frequent speed change of the transfer conveyor must be done fairly slowly, to avoid damaging the unpressed mats and because the relatively large conveyor is quite massive so its inertia makes sudden speed changes very difficult.